Structure for building a LOD for passing to the SetLODs function.
| fadeTransitionWidth | Width of the cross-fade transition zone (proportion to the current LOD's whole length) [0-1]. Only used if it's not animated. |
| renderers | List of renderers for this LOD level. |
| screenRelativeTransitionHeight | The screen relative height to use for the transition [0-1]. |
| LOD | Construct a LOD. |